For example, JP2006-203114A, which corresponds to US2009/0020319A1, describes a multilayer board including resin films having conductive patterns on a surface thereof and thermoplastic resin films made of a thermoplastic resin, which is softened with heat. The resin films with the conductive patterns and the thermoplastic resin films are alternately stacked and heat-sealed by hot pressing through a pressing machine or the like.
The multilayer board described in JP2006-203114A has a structure in which the resin film having the conductor pattern on an upper surface thereof is disposed on the resin film having the conductor pattern on a lower surface thereof.
The inventors of the present disclosure are studying to form a multilayer board by performing a hot pressing in a state where a resin base film for receiving an electronic component (e.g., LSI) thereon is stacked on a stacked body. The stacked body includes resin films having conductive patterns on a surface thereof and thermoplastic resin films alternately stacked with the resin films with the conductive patterns. To mount the electronic component on the multilayer board, terminal-connecting through holes are formed in the resin base film to expose the conductive patterns of the resin film disposed at an end layer of the stacked body from the resin base film. Electrode terminals of the electronic component are inserted into the terminal-connecting through holes of the base resin film, and connected to the conductive patterns of the resin film disposed at the end layer of the stacked body.
In such a multilayer board, however, it is difficult to properly connect the electrode terminals of the electronic component to the conductive patterns through the terminal-connecting through holes, resulting in reduction of reliability of connection between the electronic component and the conductive patterns.